scsi: libfc: Add WARN_ON() when deleting rports

The discovery rport list handling is quite odd; the list traversal is
independent from the lifetime of the rport itself. This makes auditing
quite tricky, and the chance remains that we've missed something.  So this
patch adds a WARN_ON() statement when freeing an rport which is still part
of a list.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/libfc/fc_rport.c

@@ -184,6 +184,7 @@ void fc_rport_destroy(struct kref *kref)
 	struct fc_rport_priv *rdata;
 
 	rdata = container_of(kref, struct fc_rport_priv, kref);
+	WARN_ON(!list_empty(&rdata->peers));
 	kfree_rcu(rdata, rcu);
 }
 EXPORT_SYMBOL(fc_rport_destroy);